title: Silver nanowire exposure results in internalization and toxicity to Daphnia magna.
abstract: Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physicochemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna . Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag(+) release and underwent a significant morphological transformation within 1 h following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating, and solution chemistry. Ag(+) release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag(+) and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag(+). Scanning electron microscopy imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology, and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna .
authors.affiliation: Department of Nutritional Sciences and Toxicology, University of California Berkeley , 119 Morgan Hall, Berkeley, California 94720, United States.
authors.forename: Leona D
authors.initials: LD
authors.lastname: Scanlan
authors.forename: Robert B
authors.initials: RB
authors.lastname: Reed
authors.forename: Alexandre V
authors.initials: AV
authors.lastname: Loguinov
authors.forename: Philipp
authors.initials: P
authors.lastname: Antczak
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Tagmount
authors.forename: Shaul
authors.initials: S
authors.lastname: Aloni
authors.forename: Daniel Thomas
authors.initials: DT
authors.lastname: Nowinski
authors.forename: Pauline
authors.initials: P
authors.lastname: Luong
authors.forename: Christine
authors.initials: C
authors.lastname: Tran
authors.forename: Nadeeka
authors.initials: N
authors.lastname: Karunaratne
authors.forename: Don
authors.initials: D
authors.lastname: Pham
authors.forename: Xin Xin
authors.initials: XX
authors.lastname: Lin
authors.forename: Francesco
authors.initials: F
authors.lastname: Falciani
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Higgins
authors.forename: James F
authors.initials: JF
authors.lastname: Ranville
authors.forename: Chris D
authors.initials: CD
authors.lastname: Vulpe
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gilbert
mesh_terms: D000535:Aluminum / Q000737:chemistry; D000818:Animals; D003621:Daphnia / Q000187:drug effects*; D020869:Gene Expression Profiling; D006458:Hemolymph / Q000187:drug effects; D007928:Lethal Dose 50; D053768:Metal Nanoparticles / Q000633:toxicity*; D053770:Nanowires / Q000633:toxicity*; D010100:Oxygen / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D018030:Silver Compounds / Q000737:chemistry / Q000633:toxicity; D018675:Toxicity Tests; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D018030:Silver Compounds; D014874:Water Pollutants, Chemical; D012834:Silver; D012822:Silicon Dioxide; D000535:Aluminum; D011205:Povidone; D010100:Oxygen